Motor control



Dec. 12, 1933. KRUM MOTOR CONTROL Filed April 15. 1932 FIG. 3

INVENTOR HOW/42D L. KPUM BY I , ATTQRNEY Patented Dec. 12, 1933 UNITED STATES MOTOR CONTROL Howard L. Krum, Kenilworth, 111., assignor to Teletype Corporation, Chicago, Ill., a corporation of Delaware Application April 15, 1932. Serial No. 605,467

9 Claims.

This invention relates to motor control systems for printing telegraph apparatus using signaling currents of positive and negative polarity.

The .principal object of the invention is to provide in a printing telegraph system a motor control arrangement responsive in accordance with the polarity of the line current to control automatically a normally inert driving motor.

The above and other objects of this invention m are accomplished by the provision of electromagnetic means controlled by the line signals for causing the operation or non-operation of a contact mechanism functioning to start or stop the motor dependent of the character of the current 15 on the line. Specially the invention contemplates an electromagnet operative simultaneously with the operation of the selecting electromagnet of the receiving printer and cooperating with a lever which is operated periodically from a cam 2o shaft of the printer for opening or closing the electrical circuit of the driving motor for spacing and marking current conditions respectively and for opening the motor circuit due to an absence of current on the line. :5 The improved motor control system and devices herein shown are adaptable for use with any type of printing telegraph apparatus, but are shown associated with the mechanism disclosed in U. S. Patent 1,821,110 to S. Morton et al., issued September 1, 1931.

A clear understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawing, wherein, I

Fig. 1 shows the mechanism of the motor control device in association with the mechanical parts on the printing telegraph apparatus.

Fig. 2 shows the circuit within a single station, and

Fig. 3 shows a line circuit comprising a controlling oflice and several stations in series.

Referring to Fig. 1, a shaft 1 is the operating shaft of the printing telegraph machine and ordinarily turns at about 400 revolutions per minute, being geared down from a motor shaft 2 by spiral gears 3 and 4. The shaft 1 has an extension carrying a worm 5 which drives a worm wheel 6 at a speed of about revolutions per minute. The wheel 6 drives a shaft 7 which carries a cam 8 which operates a follower 9 pivoted at 25. A bellcrank 10 having arms 11 and 12 is pivoted at 13 upon the follower 9, the pivot 13 being operated up and down alternately by the follower 9. A test finger 14 upon the arm 11 engages a shoulder 15 upon an armature 16,

of an electromagnet 18, when the bellcrank 10 is moved down, and if the armature. 16 is; in its released position as shown. Should the test finger 14 engage the shoulder 15, then the pivot 13 will continue to move downward and the arm 0 12 will be forced to open a switch 1'? by the turning of the bellcrank 10 upon the pivot'13. However, should the electromagnet 18 be energized at any time after the finger 14 has engaged the shoulder 15 and before the switch 17 has been opened, then the finger 14 will pass the shoulder 15 and ride upon the surface of the armature 16, thus permitting the follower 9 to complete its downward movement without opening the switch 17. When cam 8 has passed the follower 9, the 7 follower 9 rises by tension of spring 19 andthe cycle is repeated 6 seconds later. The bellcrank 10 is tensioned by a spring 20 extending from the arm 11 to the follower '9. Armature 16 is tensioned by a spring 21 and is adjusted by a stop 7 22 fixed in lug 23 upon the frame 24.

Referring to Fig. 2, the circuits are shown for the mechanism of Fig. 1. A motor 30 drives the shaft 7 at slow speed and the switch 17 opens the circuit of the motor 30 to stop the motor. I so The power mains 31 maybe alternating or direct current. A polar relay 32 has its contacts in series with the electromagnet 18 in a circuit from positive sign through one of the electromagnets 18 through the contacts of relay '32 and 35 through the other of the 'electromagnets 18 to negative sign. The source of power for the electromagnets 18 may be alternating and may be derived from the connections 31 if the electromagnets 18 are of proper design. The polarized relay 32 has a mechanical biasing spring 33 extending from the armature 34 to an adjustment screw 35. The polarized armature 36 is the operating armature of the telegraphic printer and for the purpose of this application is intended as illustrative of the printing telegraph receiver which is fully disclosed in the aforementioned patent. The winding 37 of the selecting electromagnet of the printer and the winding 38 of the polar relay 32 are connected in series in the circuit of line 40.

Referring to Fig. 3, the line 40 is shown wit three telegraph stations each comprising a printer 36 and a polarized relay 32, the line being connected to a central oflice comprising a service switch 41 and a transmitting relay 42 whose armature 43 connects the line 40 to positive or negative source of current alternatively for sig-, naling; The switch 41 will open the line and leave it without current for extended periods of idleness of the system.

The operation of the system is as follows:

The polar relay 32 holds its armature 34 against its left hand contact in response to marking current in the line which results in holding the electromagnets 18 energized and holding the armature 16 attracted so that the shoulder 15 will not obstruct the finger 14, the bellcrank 10 will not be rotated upon its pivot 13 when the follower 9 moves downward and the switclrl'l will not be opened so that the motor 30 will operate continuously. The short signals or spacing 7 current of reversed polarity as customarily used in printing telegraph systems of this nature will operate the polar relay armature 34 momentarily to the right thereby permitting the armature 16 to move momentarily to the right from time to time, but not for a period of time sufiicient to permit the bellcrank 10 to open the switch 17. However, should the central station place a specing signal continuously upon. theline circuit for a period of six secondsor more, the polar relay 12 will move its armature to. the right, they electromagnets 18 will be deenergized, the armature 16 will move to the. right positioning the shoul-v der 15 in the path of the finger 14 during that period, the cam 8 willforce the follower 9 downward, the finger 14 will engage the shoulder 15, the bellcrank 10 will rotate upon its pivot 13 and the arm 12 will open the switch 17 to stopthe motor.

At the beginning of the first subsequent marking signal in the line, the polar relay 32 will operate its armature to close its contacts to energize the electromagnets 18 which will attract the armature l6 and withdraw the shoulder 15 from the engaging finger 14 thereby releasing this and permitting the tension of the spring member of the switch 17 to overcome the tension of the spring 20 to rotate the bellcrank 10 clockwise upon its pivot 13 to allow the switch 17 to close and start the motor 30. In this action the finger 14 passes beyond the shoulder 1.5 along the outside surface of the armature 16.

Should the line be opened by the switch 41 thus terminating all current in the line circuit, the spring 33 will operate the armature 34 mechanically toward the right thereby producing the exact efiect described above in response to a spacing signal and the motor will be stopped in the same manner.

It has been the custom in installations of the character described to cause the motor to be stopped upon a prolonged marking signal in the line. This in some instances is undesirable because at the resumption of signaling in a high speed printing telegraph system using the Baudot system of signaling the first code combination, representing the first letter of the message, will be lost or misprinted because the motor will not attain the full speed within so short a time limit. To secure proper operation in a system which stops the motor upon a marking signal it is required that a starting signal be sent to start the motor in advance of sending the first intelligence signal to be recorded. In this feature, this invention accomplishes a new and useful result in that the motors may be stopped at will by a spacing signal and no special starting signal is required for the motors since a return to marking current is required by the transmitters and. receivers.

In systems operated by polar current in which the starting and stopping of the-motor is controlled by the position-of a polar armature, it will be obvious that should the polar armature occupy its motor-running position and should the current be removed from the line as by the switch 41, the position of the polar armature would not change and the motor would be left running during the long period of idleness of the telegraph line. In this detail this invention offers a new and useful result as compared with the prior art because, regardless of the position of the polar armature 36 in 2 when the line current is interrupted, the armalure 34 will move to stop the motor.

Although the invention has been described in connection with a specific form thereof, it will be understood that it has further applications and it is no: intended to be limited in scope by the embodiment shown herein for illustration.

The invention claimed is:

1. In a printing telegraph system, a telegraph line, a telegraph station, a motor control device at said station, a motor thereat, and means in said motorcontrol device to cause the motor to start in response to a polar marking signal in said line and to cause said motor to become inert under other conditions.

2. In a printing telegraph system, av telegraph line, a telegraph station, a motor control device at said station, a motor thereat, electromagnetic means in said motor control device to cause the motor to start in response to a polar marking current said line, electromagnetic means in said motor control device to cause said motor. to stop in response to an extended period of polar spacing current in said line, and mechanical means in said mo or control device to causesaid motor to stop in response'to an extended period of absence of current in said line.

3. In a printing telegraph system, 'a telegraph line, a telegraph station, a motorat said station, a motor control device at said station, electromagnetic means in said motor control device and connected in said line and responsive to marking and spacing signal conditions in said line, to control the starting and stopping of said motor, and mechanical means in said motor control device to cause said motor to stop in the absence of electromagnetic control.

4. In a printing telegraph system, a motor, a line circuit, a polar relay in said line circuit responsive to marking current to start said motor and responsive to spacing current to stop said motor, and a mechanical bias in said relay to operate said relay mechanically to stop said motor in the absence of marking and spacing current in said line circuit.

5. In a motor control system, a motor,,a telegraphic line circuit, a polar relay in said, line circuit responsive to marking and spacing currents to control said motor, and a local biasing means in said relay to operate said relay locally to stop said motor in the absence of controlling current in said line circuit.

6. In a printing telegraph system, a motor, a line circuit, a relay operable to control said motor in response to marking and spacing currents in said line circuit, and a local biasing means in said relay to operate said relay locally to stop said motor in the absence of control from said line circuit.

'7. In a printing telegraph system, a telegraph line, a telegraph station, a motor at said station, a motor control device at said station, polarized means in said motor control device to cause said motor to operate in response to polar current signals in said line. and mechanical springs in said motor control device to cause said motor to be non-operative under the condition of no current in said line.

8. In combination, in a start-stop telegraph system, selector mechanism, a source of power, electromagnetic means responsive to received code combinations of polar marking and spacing impulses for variably controlling the application of said source of power to said selector mechanism, means controlled by the stop impulse condition of said code combinations for rendering said source of power operative, means controlled by the reverse polar condition for rendering said source of power non-operative and further means for rendering said source of power non-operative.

9. In combination, a selector mechanism, a motor, a signaling line, a telegraphic signaling magnet and a relay connected in series in said signaling line, said electromagnet being responsive to a code of predetermined character over said signaling line for rendering said selector mechanism operative, an electromagnet controlled by said relay in response to an impulse of predetermined polarity in said'signaling line to start said motor, said electromagnet controlled by said relay in response to current of reverse polarity in said signaling line to stop said motor, and further means independent of current in said line to stop said motor.

HOWARD L. KRUM. 

